PR for Implement Rate Limiting and Abuse Prevention

backend/.env.development

@@ -28,4 +28,11 @@ ENABLE_DETAILED_LOGGING=true
 
 CONTRACT_ADDRESS=
 CONTRACT_ABI=
-ADMIN_SIGNER=
+ADMIN_SIGNER=
+
+# Rate Limiting Configuration
+PDF_RATE_LIMIT_WINDOW_MS=60000         
+PDF_RATE_LIMIT_MAX_REQUESTS=20         
+PDF_RATE_LIMIT_TRACK_BY_USER=true  
+
+DATABASE_URL=postgresql://postgres:password@localhost:5432/scavtools

backend/.env.example

@@ -28,4 +28,12 @@ ENABLE_DETAILED_LOGGING=true
 
 CONTRACT_ADDRESS=
 CONTRACT_ABI=
-ADMIN_SIGNER=
+ADMIN_SIGNER=
+
+
+# Rate Limiting Configuration
+PDF_RATE_LIMIT_WINDOW_MS=60000         
+PDF_RATE_LIMIT_MAX_REQUESTS=20         
+PDF_RATE_LIMIT_TRACK_BY_USER=true  
+
+DATABASE_URL=postgresql://postgres:password@localhost:5432/scavtools

backend/common/filters/auth-exception.filter.ts

@@ -0,0 +1,23 @@
+import {
+	ExceptionFilter,
+	Catch,
+	ArgumentsHost,
+	UnauthorizedException,
+} from '@nestjs/common';
+import { Response } from 'express';
+
+@Catch(UnauthorizedException)
+export class AuthExceptionFilter implements ExceptionFilter {
+	catch(exception: UnauthorizedException, host: ArgumentsHost) {
+		const ctx = host.switchToHttp();
+		const response = ctx.getResponse<Response>();
+		const status = exception.getStatus();
+
+		response.status(status).json({
+			statusCode: status,
+			message: exception.message,
+			error: 'Unauthorized',
+			timestamp: new Date().toISOString(),
+		});
+	}
+}